1. Field of the Invention
The structure of the present invention has utility for clamping and grounding a conduit to a support member such as a cable tray. The clamping and grounding device is designed to rigidly secure a metallic conduit to a metallic support structure and to provide an electrical ground therebetween which is capable of carrying large fault currents.
2. Description of the Prior Art
Some prior art devices have provided for a separate bonding strap, thereby requiring additional components and increased installation time. Another prior art device which contemplates the elimination of the separate bonding strap provides a specially shaped and modified U-bolt which includes a bent over portion for extending under one side of the support member and which has legs extending through a pair of saddle members between which the conduit may be clamped when nuts are coupled to the threaded ends of the bolts. The grounding connection is achieved by providing threaded holes in the lower saddle member and turning screws therein until the ends of the screws provide a pressure contact with the upper side of the support member. This structure has the disadvantage that if the grounding screws are not tightened, or are not adequately tightened, a satisfactory ground connection may not be achieved. Grounding of the conduit and support member provides two separate and distinct functions. The grounding or bonding of the metallic conduit and the support member, and all other exposed metallic surfaces, helps to provide an equipotential environment wherein the possibility of shock is greatly reduced. However, proper bonding or grounding can also serve to protect equipment and minimize fire hazards. More specifically, a fault condition may connect a live wire to the exposed metallic framework and, depending upon the nature of the fault, current of many thousand amperes can be involved. In order to safely conduct large fault currents, a conduction path of substantial cross-sectional area and low resistance is required. In one prior art device described hereinabove, the grounding is provided by means of a set screw, or screws, bearing on the support member. The current carrying capacity of such screws is limited and, therefore, when there is a large fault current, excessive heating and possible melting of the set screws and/or adjacent support member is probable. This will initiate severe arcing which may cause loss of ground and fire and/or other damage.